1. Field of the Invention
The present invention relates to an information storage apparatus of a recording medium, and more particularly, to an information storage apparatus using a magnetic medium which is coated with a wear-resistant thin film as a recording medium.
2. Description of the Related Art
One of conventional information storage apparatuses of recording media using a dielectric applies “0” or “1” depending on a polar direction of a dielectric polarization to record information, sense the information using a conductive probe, and reproduce the information.
FIG. 1 is a schematic view of a conventional information storage apparatus of a recording medium using a dielectric. Referring to FIG. 1, a conventional information storage apparatus of a recording medium using a dielectric includes a recording medium 8, a head 9, and an optical system 100. Here, the recording medium 8 includes a circular substrate 8a, an electrode layer 8b that is stacked on the circular substrate 8a, and a ferroelectric layer 8c that is stacked on the electrode layer 8b. The head 9 includes a micro tip 9a, which forms a dielectric polarization to record information and reciprocates a section of ¼ of an optical wavelength in a direction vertical to the surface of the recording medium 8, and a reflector 9b for reflecting light depending on polarity of the dielectric polarization. The optical system 100 senses differences in a light path according to the vertical reciprocation of the head 9 to detect recorded information.
As shown in FIG. 2, the recording medium 8 has a structure in which the electrode layer 8b and the ferroelectric layer 8c are sequentially stacked on the circular substrate 8a. 
The head 9 includes the micro tip 9a which directly forms a dielectric polarization on the ferroelectric layer 8c to record information and reads information depending on polarity of the dielectric polarization, the reflector 9b for reflecting light, and an arm 9c for supporting the reflector 9a, as shown in FIG. 3.
The optical system 100 includes a laser diode 1 that is a light source 1, a collimating lens 2, a beam splitter 3, an object lens 4, a condensing lens 6, and a light detector 7. Here, the collimating lens 2 collimates light emitted from the light source 1. The beam splitter 3 passes collimation light from the light source 1, but converts the path of light reflected on the surface of the recording medium 8 to direct the path to the light detector 7. The object lens 4 focuses the collimation light on a track of the recording medium 8. The condensing lens 6 condenses reflected light. The detector 7 converts condensed light into an electric signal.
The conventional information storage apparatus of the recording medium 8 using a dielectric polarizes a limited part of the ferroelectric layer 8c using the micro tip 9a to store information. Also, the conventional information storage apparatus moves the micro tip 9a, to which a predetermined voltage is applied, on the recording medium 8 to raise or fall the micro tip 9a by λ/4 depending on differences in electrostatic force between a polarized portion and a unpolarized portion or an inversely polarized portion. Thus, only light having a light path difference of λ/2 is split in the beam splitter 3, incident on the light detector 7, and detected in the light detector 7. As a result, information is reproduced.
The conventional information storage apparatus of the recording medium 8 using a dielectric use a principle of storing information depending on a polarization direction of a dielectric to sense the polarization direction of the dielectric in a state that the micro tip 9a does not contact the dielectric layer 8c when sensing information in a recording medium. Thus, sensitivity and resolution are deteriorated. Also, polarizations of the dielectric layer suffer from retention losses as time passes by and thus the capability of information storage is decreased.
A conventional information storage apparatus using a magnetic medium changes the magnetization direction of a recording medium to store information. Also, to reproduce information, the conventional storage apparatus detects a resistance change in a read head due to magneto-resistance effect when the head scans the surface of the magnetic medium. A hard disk drive is given as an example of the conventional information storage apparatus using the magnetic medium.
FIG. 4 is a schematic view of a conventional hard disk drive. Referring to FIG. 4, the conventional hard disk drive includes a disk 13, a spindle motor 15, an actuator 23, a voice coil motor (VCM) 21, a flexible printed circuit (FPC) 11, and a bracket (not shown). Here, the disk 13 records information and the spindle motor 15 rotates the disk 13. The actuator 23 has a magnetic head 25 which records information on the disk 13 and reproduces information from the disk 13. The VCM 21 actuates the actuator 23. The FPC 11 transmits an electric signal from a printed circuit board (PCB) to the actuator 23. The bracket supports the FPC 11.
The disk 13 is a recording medium which is formed by coating a metal circular plate with a magnetic material. The disk 13 has a parking zone that is minutely manufactured by a laser in an inner region of the disk 13 and combined with the spindle motor 15 to stably place the magnetic head 25 on the disk 13 when power is turned off and a data zone on which a magnetic signal is recorded outside the parking zone. In the data zone, a servo signal for informing the position of information to be recorded is recorded on tens of thousands of tracks along the circular shape of the disk 13 in advance.
The actuator 23 includes a fantail 19, a pivot bearing 17, and a magnetic head 25. The fantail 19 has the VCM 21 which actuates the actuator 23. The pivot bearing 17 serves as a pivot of the actuator 23. The magnetic head 25 has a write head for recording information on the disk 13 and a read head for reproducing information from the disk 13.
To record information on the conventional hard disk drive, the write head moves with the rotation of the actuator 23 by an electric signal applied to the PCB to magnetize a desired track using a magnetic field during the rotation of the disk 13. The actuator 23 re-rotates to sense the magnetic direction of the disk 13 using the read head to reproduce recorded information as previously described.
In the conventional hard disk drive, the magnetic head 25 does not contact the disk 13 during the operation of the disk 13 due to floating force occurring when the disk 13 rotates. In the conventional hard disk drive, the magnetic field is widened as the height of the magnetic head 25 is higher. However, the smaller amount of information is recorded. Thus, an attempt to increase the integration of information by lowering the height of the magnetic head 25 has been made. However, as the distance between the disk 13 and the magnetic head 25 is reduced, the probability that the disk 13 will contact the magnetic head 25 increases. If the disk 13 contacts the magnetic head 25, the high-speed rotation and the highly hard surface of the disk 13 may damage the magnetic head 25 or information.